Is there any way I can use cocoa powder instead of chocolate, as I don't have any ? :/ please reply.

Not really. Cocoa powder isn't the same as chocolate (not even 100% cacao chocolate). It's only one part of the ingredients (the other part being the cocoa butter which has been removed to make cocoa powder). You might be able to get it to work by adding other ingredients, but I wouldn't know where to start without a lot of experimenting... easier to just buy chocolate.

This microwave method prevents burning the chocolate by adding it at the end: mix condensed milk, butter & sugar. Microwave 3 minutes. Take out and stir. Microwave another 3 minutes. Take out and stir again. Microwave another 3 minutes. Sitr in chocolate. The chocolate melts due to the heat, but never gets microwaved. Magic! Cadbury chocolate melts work very nicely - using whilte chocolate with brown sugar (instead of white) makes a delicious caramel flavor fudge.

I make fudge for Christmas gifts every year. It's not even requested anymore. It is EXPECTED! Anyway, I use 1 package of almond bark to 1 can of condensed milk, melt together. Take off the burner add flavoring, color, nuts, candy, etc. Pour into buttered dish and let sit.
For Maple I use white almond bark and mix in 1 1/2 tsp. maple flavoring. I have made white with vanilla and add chopped up candied cherries. I have made bananna fudge, raspberry, cherry, etc. Make the white fudge and add 1 1/2 tsp of whatever flavoring suits you. If you want color use food coloring gel (not liquid). They do have chocolate and butterscotch almond bark if you would rather just have those flavors.

I have been making this fudge for years and it is allways good. I heat the condensed milk in a glass microwave bowl first in microwave untill it starts to boil let boil for about 3 minutes.take out and add rest of ingredients. stir untill it starts to thicken about 1 minute. our into tin foil lined dish and refrigerate about 2 or 3 hours untill firm. You can takel foil off with no trouble.